NEW DELHI: Manmohan Singh, India's third-longest serving Prime Minister, is signing out of office in typically low-key but diligent style. On Tuesday, he said goodbye to the staff of about 110 in his office, some of whom burst into tears. He then cleared several files that had been stuck for one reason or the other, including a big-ticket $231 million investment in a local pharmaceutical company.

Singh, who faced harsh criticism for appearing to be a mute spectator on critical issues that snowballed into major scandals and hurt his government's credibility, will address the nation one last time soon after the Lok Sabha results are out on May 16.

In what would be his 1,200th speech since assuming office in May 2004, Singh's message to the nation is likely to focus on the "promise and untapped potential of the idea of India" and could be interpreted as a wish list for his successor in office, said a person with knowledge of the content.

Singh, who announced nearly six months ago that he won't be available for a third term at the top, will move to 3, Motilal Nehru Marg from his official 7, Race Course Road residence, but will serve in the Rajya Sabha until 2018.

He's learnt to have already handed over all the high-value gifts he received in his official capacity during his 10-year tenure and is now in the process of deciding which books in his library can keep him company in his new 2.5 acre abode.

If the election results match the exit polls reported so far, officials expect Singh to be considered for the post of leader of the Opposition in the Upper House.

The longest-serving Prime Minister outside the members of the Nehru-Gandhi family, Singh also chaired a cabinet meeting Tuesday to clear the Rs 1,400 crore investment proposed by American private equity firm KKR in Hyderabad-based Gland Pharma and its subsidiary.